gistfile1.txt

        public override Task ApplyActionAsync(RewriteContext context, BackReferenceCollection ruleBackReferences, BackReferenceCollection conditionBackReferences)
        {
            var response = context.HttpContext.Response;
            response.StatusCode = StatusCode;

            if (!string.IsNullOrEmpty(StatusReason))
            {
                context.HttpContext.Features.Get<IHttpResponseFeature>().ReasonPhrase = StatusReason;
            }

            context.Result = RuleResult.EndResponse;

            context.Logger?.CustomResponse(context.HttpContext.Request.GetEncodedUrl());

            if (!string.IsNullOrEmpty(StatusDescription))
            {
                var content = Encoding.UTF8.GetBytes(StatusDescription);
                response.ContentLength = content.Length;
                response.ContentType = "text/plain; charset=utf-8";
                response.Body.Write(content, 0, content.Length);
            }

            return TaskCache.CompletedTask;
        }

return response.Body.WriteAsync...

Also, since the StatusDescription is constant, you could Encoding.UTF8.GetBytes(StatusDescription); move to the constructor

regarding StatusDescription, i'm not following you. it may or may not be set. are you suggesting making additional constructor overloads to account for the combination of possible parameters? i can add:

public CustomResponseAction(int statusCode, string statusReason, string statusDescription)

but can't account for the other two individually since they share the same signature. that's why i initially went with settable properties. if it's valid to say that you can't/won't have a StatusDescription without also having a StatusReason, then that's obviously doable.

what do you suggest?